I must have used not less than 6 different tones of pigments from AK-Interactive and Mig to make 4 different shades of pigments, from the lightest to the darkest one.

On the lower hull, I simlpy spread some pigments in a random pattern that I drowned with Tamiya Thinner to fix them. I also spread some more pigments on the most humide surfaces to give it a gritty look. Nothing too complicated here, but I nevertheless tried to keep the darker tones around the most exposed to mud areas.

Then, on the upper parts, horizontal and vertical, it was a little trickier. I really used a small amount of pigments in order not to cover the previous work with oils. Here's the technique. Apply the pigments with a fine brush, crush them into the paint so that they can get a hold onto the surface, but nevermind the small parts of pigments that are still workable. I work with only one color at a time that I fix with airbrushed Tamiya Thinner. I have a 0.4 bar pressure and the airbrush is held far from the model. I simply make the thinner rain over the pigments, giving them a gritty aspect. I repeat this operation as many times as necessary. The rear part of the JSU isn't worked yet, for I'm waiting for the lower hull to be fixed to get uniform effects.

Once again, I would like to thank Michael Rinaldi for his wise advice and strongly recommand you to read his books, TANKART 1 and TANKART 2.